For many years hockey players have been using hockey sticks having curves in the blade on the forehand side. This forehand curve enables players to project a hockey puck with greater accuracy on a forehand shot, as compared to a stick with no curvature, known as a neutral stick. For various reasons, the curvature of hockey stick blades has now been restricted by hockey officials.
While curved sticks improve forehand shots for most hockey players, they simultaneously increase the difficulty of projecting a puck with a backhand shot. This is due to fact that, because of the concave forehand curve, there is less flat blade area on the backhand side to use for hitting or slapping the puck. Furthermore, the forehand curve makes it more difficult to hold or control the puck from the backhand side. This is particularly true for school-aged players.
The standard design for a hockey stick comprises an elongated handle or shaft portion disposed at approximately a 90 degree or slightly greater angle with respect to the handle. These sticks are commonly made of wood, plastic, or composite materials such as fiberglass. It has been common to blades that are curved in a forwardly direction to improve puck control and forward shooting ability. The disadvantage of a curved blade, however, is that the curvature adversely affects backhand shots because the puck may slide or be deflected off the convex rear surface instead of being squarely hit in the desired direction of travel.
Recently, this problem has been addressed by the development of dual-blade hockey sticks comprising a split or bifurcated blade in which the front (forward-facing) blade toe is forwardly concave and the rear (rear-facing) blade toe is substantially flat. Such dual-blade hockey sticks are described in U.S. Pat. No. 4,570,932 issued to George R. Cote and U.S. Pat. No. 4,793,613 and U.S. Pat. No. 4,799,682 each issued to Owen P. Hughes.
The Cote patent utilizes a wedge of relativity soft material positioned at the tip of the blade in order to create a winged tip resulting in a forward surface curvature while retaining a more or less flat rear surface while each of the Hughes patents describe a dual-blade hockey stick in which there is no separating spacer or wedge between the "toes" of the blade (as in the Cote stick) thereby, permitting the forward and rear toes to flex independently.
Most ice hockey blades are laminated with wood and/or fiberglass. The individual laminae or plies are held together with some type of adhesive bond. These adhesive-type bonds work fine when supporting in-plane shear loads but not the inherent tensile load associated with the dual-blade sticks, especially where the forward and rear toes flex independently as in the Hughes hockey stick. On the other hand, street hockey sticks are typically molded in plastic as one material.
For both laminated and molded constructions however, an open V-shaped blade is extremely susceptible to fracture. Out-of-plane (plane of blade) or through-the-thickness tensile stresses cause fracture by the formation of cracks or delimitations between the separate blades originating near the root of the V-joint and propagating towards the heel. A fulcrum effect was found to exist in the vicinity of the V-joint. In other words, displacement of points located before the root would be opposite in sense from those located beyond the root. Blade forces resulting from slapshots, backhand shots, and so forth, induced out-of-plane tensile stresses localized in the vicinity of the root. These detrimental tensile stresses are an inherent characteristic of the bifurcated blade geometry and exist in both laminated (ice) and molded (street) hockey blades.
Indeed, recent experience with the existing dual-blade hockey stick has confirmed that in use these sticks have a relatively short and unsatisfactory playing life. Stresses and strains generated by repeated striking of the hockey puck, other players sticks, the ice (or ground), and so forth rapidly lead to stress fractures at and behind the point of bifurcation or crotch of the dual-blade leading to eventual separation and premature failure.